<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    div{
    width: 100px;
    height: 100px;
    border: 1px solid red;}
    #d1{
      /*margin-left: 50px;*/
      /*margin-top: 50px;*/
      /*margin-bottom:50px;*/
      /*margin-right:50px;*/
      margin: 50px;/*四个方向赋值*/
      margin: 50px 100px;/*上下50左右100*/
      margin: 0 auto;/*上下0左右自动（居中）*/
      margin: 10px 20px 30px 40px;/*上右下左顺时针赋值*/
    }
    #d2{
      /*上下相邻两个元素彼此添加外边距，取最大值*/
      margin-top: 50px;
    }
    #s1{
      /*行内元素上下外边距无效*/
      margin-left: 50px;
      margin-bottom:50px;
    }
    #s2{
      /*左右相邻彼此添加外边距，两者相加*/
      margin-left: 50px;
    }
  </style>
</head>
<body>
<span id="s1">span1</span><span id="s2">span2</span>
<div id="d1">div1</div>
<div id="d2">div2</div>
</body>
</html>